Monitoring has always been a challenge to nature conservationists. The first instinct of biologists is to attempt to measure change through replicated, statistically sound, recording of species abundance and cover. This traditional approach can produce the required results, but the cost is very high if variance between recorders or seasons is controlled. With over 3,800 SSSIs in England alone the real challenge is to develop monitoring methodologies which can be applied across all SSSIs in a manner which is consistent across Great Britain, and which meet the needs of European legislation. The challenge facing the statutory agencies is to achieve this within their restricted budgets without recourse to the expensive traditional approaches on every site. In 1995 the response was to develop a model which defines favourable condition and limits of acceptable change for each feature of a site, then establish criteria against which assessments could be made of site condition against defined objectives.